1. Field of the Invention
The present invention relates to a sorter which sorts and stacks articles to be treated on receptacles such as trays, the article including, for example, sheets discharged from photocopiers, printers and the like.
2. Description of the Prior Art
Generally, a conventional sorter which deals with sheets as articles to be treated sequentially shifts trays to be placed in an open state for receiving a sheet, and then the sorter stacks sorted sheets on trays in the open state by discharging the sheets on them.
In a sorter equipped with a stapler, sheets stacked on trays are stapled with the stapler.
Conventional mechanisms for placing trays in the open state during sequential shifting of the trays include a mechanism with Geneva wheels as disclosed in U.S. Pat. No. 4,466,608, for example. In the mechanism, tray pins of trays are aligned and guided in respective vertical slots for vertical displacement. The tray pins are engaged with grooves of corresponding Geneva wheels one by one, and are thereby shifted upwardly or downwardly. In this manner, the open state is attained by enlarging a space between a tray, of which tray pins are moved, and another tray just above or below the tray. Tray pins which are to be downwardly moved by the Geneva wheels are engaged with grooves of the corresponding Geneva wheels by gravity whereas tray pins which are to be elevated by the Geneva wheels are fitted in grooves of the corresponding Geneva wheels by upwardly biasing of a bissing mechanism such as a spring.
The conventional sorter is, however, disadvantageous in that trays are rather vibrated due to impacts produced on engagement of the tray pins to be upwardly moved with grooves of the Geneva wheels since the engagement is achieved by biasing the tray pins upwardly. Moreover, strong springs must be provided to attain positive engagement. There is the same problem in a sorter with receptacles of article to be treated which receptacles operate in the same manner as the trays; for example, a sorter with receptacles which operate to sort articles other than sheets.